Asymmetric Synthesis of the Tricyclic Core of <i>Calyciphylline</i> A‑Type Alkaloids via Intramolecular [3 + 2] Cycloaddition

Asymmetric synthesis of the [5–6–7] tricyclic system common to the <i>Calyciphylline</i> A-type alkaloids is reported, featuring Overman rearrangement, Heck cyclization, intramolecular [3 + 2] cycloaddition, diastereoselective hydrogenation, and Claisen rearrangement as strategic events. The approach is capable of installing the crucial carbonyl functionality as well as multiple stereogenic centers within a congested polycyclic ring skeleton